1. Field of the Disclosure
The present disclosure relates to a method of controlling a timer in user equipment (UE).
2. Description of the Related Art
Generally, when a UE adds a public land mobile network (PLMN) to a “Forbidden PLMN List” or a “Forbidden PLMNs for General packet radio service (GPRS) service” list or sets a subscriber identity module (SIM)/universal SIM (USIM) as invalid for Non-GPRS services or GPRS services (or both), and a timer “T3245” is not running, the UE initiates the timer “T3245” with a random value (i.e., in a range between 24 hrs and 48 hrs). Further, after the expiration of the timer “T3245”, the UE removes the “Forbidden PLMN List” and the “Forbidden PLMNs for the GPRS service” list and sets the SIM or the USIM to valid for the non-GPRS services and the GPRS services. When the lists are removed, the UE performs a cell selection mechanism according to 3GPP TS 43.022 [82] and 3GPP TS 25.304 [98]. Further, if the UE is powered OFF/ON, the timer “T3245” has to be considered and based on a remaining timer period for the timer “T3245” to expire, one or more actions are to be taken.
In a situation where the UE is powered OFF while the timer “T3245” is running, when the UE is powered ON, the timer “T3245” will be restarted with a value equal to “t1−t”, where “t1” is the remaining time period for the timer “T3245” to expire at a power OFF event of the UE and “t” is the time elapsed between the power OFF event and a power ON event. If “t1” is greater than “t”, then the timer “T3245” will be restarted with the value equal to “t1−t”. Alternatively, if “t1” is less than or equal to “t”, then the UE will follow the same behavior as the UE upon expiration of the timer “T3245”. On the other hand, if the UE is not capable of determining “t”, the UE restarts the timer “T3245” with the value “t1”.
If the UE is powered OFF and again powered ON with a different SIM (i.e., a different SIM from the SIM on which the timer “T3245” is initiated), the behavior of the UE may not be defined which may lead to incorrect behavior. As per the existing specification, the UE checks the remaining time period between the power OFF and power ON and removes the “Forbidden PLMN List”. The “Forbidden PLMN List” has to be removed if the SIM that is inserted is the same as the SIM on which the “PLMN Not Allowed or GPRS Not Allowed” is received and the timer “T3245” is initiated.
As shown in FIG. 1A, where a SIM-1 is inserted in the UE, the UE sends an “ATTACH request message” to a network entity. Further, the UE receives an “ATTACH reject message” from the network entity with cause as “PLMN Not Allowed”. After receiving the “ATTACH reject message,” the UE adds the PLMN-1 to the “Forbidden PLMN List” and initiates the timer “T3245” with the value of 24 hrs; the UE is powered OFF while the timer is running. Further, the UE is powered ON after 24 hrs with a SIM-2 inserted in the UE. The SIM-2 includes a PLMN-2 and a PLMN-3 as the forbidden PLMNs. After detecting that the UE is powered ON, as the timer “T3245” duration is already completed, the UE removes the forbidden PLMNs (i.e., the PLMN-2 and PLMN-3), and the UE sends an “ATTACH request message” to the forbidden PLMN's (i.e., the PLMN-2 and PLMN-3) though the PLMNs should not be accessed. The UE unnecessarily attempts registration with the network entity, thus wasting radio resources.
As shown in FIG. 1B, where the SIM-1 and the SIM-2 are inserted in the SIM slots available in the UE (i.e., dual SIM dual standby device), the UE is powered ON with the SIM-1 and the SIM-2. Initially, the UE sends the “ATTACH request message” using the SIM-1 to the network entity. Further, the UE receives the “ATTACH reject message” from the network entity with cause as “PLMN Not Allowed”. After receiving the “ATTACH reject message,” the UE adds the PLMN-1 to the “Forbidden PLMN List” and initiates the timer “T3245” with the value of 24 hrs. Similarly, the UE sends the “ATTACH request message” using the SIM-2 to the network entity. Further, the UE receives the “ATTACH reject message” from the network entity with cause as “PLMN Not Allowed”.
After receiving the “ATTACH reject message,” the UE adds the PLMN-2 to the “Forbidden PLMN List” and initiates the timer “T3245” with the value of 24 hrs. After 23.55 minutes of the timer “T3245” using the SIM-1, the UE is powered OFF. The SIM-1 and the SIM-2 are swapped, where the timer “T3245” using the SIM-2 with PLMN-2 included in the “Forbidden PLMN List” is initiated and 10 minutes has elapsed. The remaining time period for the timer “T3245” using the SIM-2 is set to expire at 23:50 minutes. Further, the UE is powered ON, and after 5 minutes, the PLMN-2 included in the “Forbidden PLMN List” is removed and the PLMN search is performed rather than removing the PLMN-2 after 23:50 minutes. Similarly, the PLMN-1 included in the “Forbidden PLMN List” is removed after 23:50 minutes instead of removing it after 5 minutes. Due to the following reasons outlined above, there is a delay in camping and registration of the UE with the network entity, the UE may be in out of service (OOS) for longer duration, the UE may miss any mobile terminal (MT) calls or paging messages, the UE may be unable to perform any calls or services, or the like.